Recent advancement of broadband technologies has enabled high-speed, high-volume wireless communications such as cell-phone networks and public wireless LANs. Also, to meet the demand for high-volume data communications, third-generation base station amplifiers have become widely used and fourth-generation base station amplifiers will be introduced. Further, introduction of new communication schemes such as WiMAX may accelerate the advancement of high-speed, high-volume wireless communications.
Meanwhile, there is a demand for a high-power, wideband radar amplifier that can increase the detection range and resolution of a radar system. Also, it is desired to reduce the operational costs and the size of a cooler for a radar amplifier.
For a phased array radar where radar modules including amplifiers are arranged in an array in a small space, it is desired to reduce the size of the radar modules and thereby to arrange the radar modules more densely.
In a radar transceiver module, components such as an amplifier and passive elements each housed in a package are further placed in a metal high-frequency circuit package. The components are connected to each other via wiring on a printed-circuit board.
Also, there are high-frequency circuit packages with laminated structures that are made of, for example, high temperature co-fired ceramic (HTCC) or low temperature co-fired ceramic (LTCC).
A known ceramic high-frequency circuit package includes a planar dielectric layer and a frame-shaped dielectric layer formed on the planar dielectric layer. In the ceramic high-frequency circuit package, a signal conductor is formed on the upper surface of the planar dielectric layer, and first ground conductor layers are formed on the sides of the signal conductor at a distance from the signal conductor. A second ground conductor layer is formed on the lower surface of the planar dielectric layer and a third ground conductor layer is formed on the upper surface of the frame-shaped dielectric layer. The region surrounded by the frame-shaped dielectric layer forms a cavity where a semiconductor device is mounted.
The frame-shaped dielectric layer may include a feedthrough (see, for example, Japanese Laid-Open Patent Publication No. 2001-144509).
In a known configuration, the feedthrough is implemented by multiple via holes formed in the frame-shaped dielectric layer and connects the third ground conductor layer on the frame-shaped dielectric layer with the first ground conductor layers below the frame-shaped dielectric layer. Ground castellations with a semicircular shape may also be embedded in the side surfaces of the frame-shaped dielectric layer.
When via holes are used as the feedthrough, the distance between an edge of the third ground conductor layer formed on the upper surface of the frame-shaped dielectric layer and the via holes formed in the frame-shaped dielectric layer may be set at substantially zero (see, for example, Japanese Laid-Open Patent Publication No. 2000-100994).
As another example, the feedthrough may be implemented by castellation conductors formed on the surfaces of recesses formed in the inner and outer side surfaces of the frame-shaped dielectric layer (see, for example, Japanese Laid-Open Patent Publication No. 2002-190541). The castellation conductors extend laterally in directions that are orthogonal to the length direction of the first ground conductor layers. The castellation conductors electrically connect the third ground conductor layer on the frame-shaped dielectric layer with the first ground conductor layers below the frame-shaped dielectric layer, and have a width that is the same as the width of the first ground conductor layers.
In a known technology, the width of a feedthrough at the output terminal side and the widths of parts of a micro strip line, i.e., a signal line, inside and outside of the feedthrough are adjusted to keep the characteristic impedance within an allowable range (see, for example, Japanese Laid-Open Patent Publication No. 2007-081125).
Another known high-frequency circuit package includes a package wall that surrounds a high-frequency integrated circuit (see, for example, Japanese Laid-Open Patent Publication No. 2000-133735). A feedthrough for inputting and outputting signals to and from the high-frequency integrated circuit is formed in the package wall. The feedthrough includes a first microstrip line, a dielectric loaded waveguide, and a second microstrip line.
The first microstrip line is disposed inside of the package wall. The dielectric loaded waveguide is disposed to pass through the package wall. One end of the dielectric loaded waveguide is electromagnetically coupled with the first microstrip line. The second microstrip line is disposed outside of the package wall and is electromagnetically coupled with the other end of the dielectric loaded waveguide.